standard notes for flight mechanics (E) ww2

Hi All,
I finally tried some research on a book i have had for some years.

standard notes for flight mechanics (E)

stamped 10 feb 42

a pencil name of K Pearce

a large stamp
‘B/467’

RAF Innsworth Glos.

Now i always assumed it was B flight 467 Sqn

however 467 Sqn didn’t form until nov ’42.

anyone know what B/467 means ?
Was it a training course.

cheers
Jerry